Conversion and coking of carbonaceous materials



March 9, 1937. A. FISHER CONVERSIQN AND CGK-ING OF CARBONACEOUSMATERIALS.

Filed June 2,A 1953 Patented Mar. 9, 1937 PATENT OFFICE CONVERSION ANDCOKING OF CARBONA- CEOUS MATERIALS Alfred Fisher, Chicago, Ill.,assigner to Universal Oil Products Company, Chicago, Ill., a corporationof Delaware Application `lune 2, 1933, Serial No. 674,002

3 Claims.

This invention particularly refers to an improved process and apparatusfor the conversion and coking of mixtures of hydrocarbon oil and solidor semi-solid bituminous material, such as coal, peat, lignite, oilshale and the like, for the production of low volatile coke, gas, lightdistillate such as motor fuel, and intermediate liquid products,whiclilatter-maybe subjected to further conversion in the same or aseparate system or may be collected as a final `product of the process.

The preferred mixture to be treated is coal and oil.

In one embodiment the coking zone may comprise a plurality ofalternately operated coking ovens of the type wherein the mixture of oiland bituminous material to `be coked is first heated in a coilpreferably to a mild cracking temperature but insufficient to causeobjectionable coke depositions and the mixture is then introduced onto ahighly heated surface, preferably of suitable heat-conductive refractorymaterial lsuch as silicon carbide, (e. g. carborundum) fused aluminumoxide, aluminum silicate, suitable fire clays or brick and the like,upon which the result- 5 ing coke is allowed to accumulate in arelatively thin layer, to be removed by means of an hydraulic ram, or inany other suitable well known manner, after the coke layer has beenbuilt up to the desired thickness. A coking Zone of this 30 characterpermits the use of higher temperatures than are ordinarily permissiblein metal coking chambers without resorting to expensive steel alloys forthe walls of the vessel. In ovens such as described above, the heat isapplied directly 35 to the under surface of the heat-conductiverefractory material and is transmitted directly therethrough to thematerial undergoing coking and the bed of coke accumulated thereon.Coking zones of this character may be operated at 40 subatmospheric,substantially atmospheric, or

low superatmospheric pressure, are easily cleaned by the use ofhydraulic rams in a manner similar to that employed in ordinarycarbonizing retorts, and are easily adaptable to alternate operation,

45 so that the duration of the operation of the process is not limitedto the capacity of the coking retort.

One specific embodiment of the present invention may comprise subjectinga mixture of hydro- 50 carbon oil and finely divided carbonaceousmaterial to conversion in a heating coil under noncoking conditions,introducingr the heated material into a plurality of alternatelyoperated coking ovens, wherein the residual conversion products '55 arereduced to coke and the coke is substantially devolatilized byintroducing the mixture from the heating coil onto a highly heatedrefractory surface, withdrawing the vaporous products from kthe cokingovens, removing therefrom their highboiling tar-like components andsimilar high coke-forming materials, subjecting the remaining vapors tofurther fractionation whereby their components of an intermediatenature, boiling above the range of the desired final light distillateproduct of the process Aand of iower boiling nature than said heavytar-like and high cokeforming materials, are condensed as intermediatecondensate, subjecting. the fractionated vapors of the desired endboiling point .to condensation, and collecting and separating theresulting kdistillate and gas. The tar-like and similar high cokeformingmaterials separated from the vaporous products from the coking ovensmay, when desired, be withdrawn from the system to storage or to furthertreatment in another process, but preferably they are returned tofurther treatment in the same system by supplying them either direct tothe coking ovens orto commingle with the charging stock mixture suppliedto the heating coil. The intermediate condensate separately recoveredfrom the vaporous products from the coking ovens may be withdrawn fromthe system to storage, or preferably it is returned to the heating coilfor further conversion. This material ordinarily is ideal as cleancracking stock and may be supplied as such to the same or anotherprocess.

As a modification of the specific embodiment above described, it is alsowithin the scope of the present invention to supply the intermediatecondensate, or when desired, the total condensate recovered from thevaporous products from the coking ovens, to the heating coil of thesystem for conversion, introducing the heated products therefrom intothe coking ovens, in which case preferably all or a portion of thecharging stock mixture comprising hydrocarbon oil and finely dividedsolid or semi-solid carbonaceous material may be supplied direct to thecoking ovens without passing through the heating coil. This latter typeof operation permits the use of more severe conversion conditions in theheating coil, particularly when only the intermediate condensate issupplied to this zone, and may result in the production of increasedquantities of motor fuel of higher anti-knock value.

The accompanying diagrammatic drawing illustrates one specific form ofapparatus embodying the features of the present inventionv accomplished.The drawing and the following description thereof will serve to moreclearly explain the various modifications of the operation of theprocess, which however, are not to be considered equivalent but may beselected to suit the particular requirements of the material undergoingtreatment and to accomplish the desired results.

Referring to the drawing, raw oil charging stock comprising any desiredhydrocarbon oil, such as crude petroleum, petroleum residue, fuel oil,or the like, including such oils as coal tar, pitches and other heavyoils, is supplied through line I and valve 2 to pump 3, by means ofwhich it is fed through line 4 and valve 5 into mixing tank 6, whereinit is commingled and intimately mixed with other ingredients of thecombined feed for the process. Y

Coal or other suitable solid or semi-solid carbonaceous material isadded to the mixing tank, preferably in nely divided form and inregulated amounts relative to the raw oil, through a hopper or othersuitable charging device 1 of any suitable form. Mixing tank 6 ispreferably equipped with a stirring device 8 of any suitable form, bymeans of which the carbonaceous material is finely dispersed throughoutthe body of the oil and the ingredients of the combined feed aremaintained in a thoroughly commingled state. Other oils from within thesystem may be added to the materials in the mixing tank to make up thetotal combined feed for the process, as will be later more fullydescribed, and the commingled materials are withdrawn from the mixingtank through line 9 and valve I0 to pump I I, by means of which they maybe fed through line I2 and valve I3 to heating coil I4. When thecharging stock is of a heavy viscous nature it may be necessary to heatthe liquid charging stock and/or the combined feed by means of steamjacketed lines or a steam jacketed mixing tank, or in any other suitablewell known means (not shown) in order to facilitate the handling of thismaterial. When desired, heat for this purpose may be recovered fromwithin the system by means of heat exchangers or the like, (not shown).

Heating coil I4 is located within a furnace I5 of any suitable form, bymeans of which the charging material supplied thereto is heated to thedesired conversion temperature, preferably at a substantialsuperatmospheric pressure. When heavy oils and solid or semi-solidcarbonaceous material are passed through the heating coil as alreadyindicated, the size of the heating coil, the velocity of the materialspassing therethrough and the rate of heating are preferably such thatthe desired conversion temperature is reached without allowingsufficient time in the heating coil to cause any detrimental formationand deposition of coke in this zone, a high rate of heating preferablybeing employed in the furnace and a high oil velocity being maintainedin the heating coil for this purpose. The heated materials pass fromheating coil I4 through line I6, valve I'I and line I8, and areintroduced into coking oven 20 through lines ZI 2l and 2| controlled bythe respective valves 22, 22 and 22".

Coking oven 20 preferably comprises a plurality of coking chambers suchas 23, Z3 and 23, which may be alternately operated, cleaned andprepared for further operation in order to render the processcontinuous. It will be understood that any number of similar cokingchambers may be employed, although only three are illustrated in thedrawing. Each of the coking chambers has a floor 24, preferablyconstructed of A suitable refractory highly heat-conductive materialsuch as silicon carbide, fused aluminum oxide, aluminum silicate and thelike, heated to a high temperature from beneath by means of thecombustion of any suitable type of fuel in combustion zones 25. Theheated products from heating coil I4 are introduced onto the highlyheated floor of one or more of the coking chambers whereby the oil iscoked and the coke is allowed to accumulate in a relatively thin layerto a depth of approximately 6 inches, more or less, over the highlyheated floor, following which heating may be continued for a time inorder to devolatilize the coke to the desired degree, during which theoil is diverted to another coking chamber, and finally the layer ofdevolatilized coke is removed by means of an hydraulic -ram or any othersuitable well known manner, following which the chamber is prepared forfurther operation. Vaporous products are withdrawn from the cokingchambers through lines 26, 26 and 26, controlled by valves 27, 21 and2l, respecttively, and pass through line 28 into a fractionator and tarseparator 29, in the lower portion of which their heavy components ofhigh cokeforming characteristics, such as tars and the like, are removedfrom their lower boiling components, which latter are furtherfractionated for the separation and removal of intermediate condensatesboiling above the range of the desired final light distillate product ofthe process and of lower boiling characteristics than said heavy highcoke-forming materials.

Fractionated vapors of the desired end boiling point are passed,together with gas produced by the operation, from the upper portion offractionator 29 through line 30 and valve 3l to be subjected tocondensation and cooling in condenser 32. The resulting distillate andgas pass through line 33 and valve 34 to collection and separation inreceiver 35. Gas may be released from the receiver through line 36 andvalve 3I. The distillate may be withdrawn from this zone through line 38and valve 39 to storage or to any desired further treatment. Whendesired, a portion of the distillate collecting in receiver 35 may bereturned by well known means not shown in the drawing to the upperportion of fractionator 29, serving as cooling and refluxing medium inthis Zone to assist fractionation of the vapors and maintain the desiredvapor outlet temperature from the fractionator, thus controlling the endboiling point of the final light distillate product of the process.

In the preferred operation of the process subatmospheric pressures orvacuum are employed in the coking chambers and, in order to avoidpassing the hot vaporous products from the coking oven through a vacuumpump or compressor, sub-atmospheric conditions are also preferablymaintained in the succeeding ractionating, condensing and collectingportions of the system. A pump or compressor 48 may be provided, asillustrated in the drawing, for the purpose of withdrawing gases fromreceiver 35 through line 4I and valve 42, discharging the same throughline 43 and valve 44 to a gas-holder, or elsewhere as desired, for thepurpose of maintaining the desired sub-atmospheric pressure in thecoking oven and succeeding portions of the system.

High boiling oils, tars and the like of high boiling and easy cokingcharacteristics separated from the vaporous products from the cokingoven in the fractionator and tar separator 29 are withdrawn from thelower portion of this zone through line 45 and valve .46 to pump 41,-from which they are passed through line 48y and may be discharged, allor in part, from .the system through line 49 and valve 59, to storage orfurther treatment outside of the system, as desired. Preferably,however, a regulated portion or all of this material passes from line 48through line 5| and may be returned by means of line 52, valve 53, lineI3 and lines 2|, 2|' and 2|, through the respective .valves 22, 22 and22", into the coking chambers for further treatment and reduction tocoke or, When desired, `this material may be returned to furtherconversion in heating coil I4 by passing the same from line 5I throughline 54, valve 55ancl line I2 directly into heating coil I4, or bypassing it through valve 56 in line 5| and through line 19 into mixingtank 6 to commingle with the charging stock mixture subsequentlysupplied to the heating coil.

Intermediate condensates recovered from the vaporous products undergoingfractionation. may be withdrawn as one or a `plurality of side streamsfrom fractionator 29, for example, through line 51 and valve 58 tocolumn 59, wherein they may be reboiled by means of steam introducedthrough line 60 and valve 6|, or in any other suitable well known mannerto vaporize any components within the boiling range of the desired finallight distillate product of the process and to free theV oil of anyentrained gases. The vapors evolved by reboiling the intermediatecondensates may be returned to fractionator 29 through line 62 and valve63. The reboiled intermediate condensates may pass from column 59through line 64 and valve 65 to pump S6. It will be understood that suchrebciling of the intermediate products is not essential to the operationof the process and may be omitted when desired. The intermediatecondensate passes from pump 66 through line 61 to the heating coil forfurther conversion, or it may be discharged from the system to storage,or to conversion in another cracking system or elsewhere as desiredthrough line 68 and valve B9. When the intermediate condensate isreturned to further conversion in heating coil I4, it is passed throughlines 51, 19, 1I, valve 12 and line I2 direct to heating coil I4, or maypass throughr valve 13 in line 19 into mixing tank 6 to commingletherein with the other ingredients of the combined feed supplied toheating coil I4.

When liquids are supplied from within the system, as already described,to mixing tank 6 they may, when desired, be cooled by well known means,not shown in the drawing, prior to their introduction into this Zone.However, when it is desired to conserve the heat remaining in theseproducts and in case it is not desirable to supply them direct vtoheating coil I4, as has been previously described, or when the chargingstock is preheated, prior to its introduction into the mixing tank, orwhen heat is supplied to the mixing tank by means of a steam coil orsteam jacket or the like, mixing tank 5 may be operated at substantialsuperatmospheric pressure in order to minimize vaporization in this Zoneand is preferably well insulated to conserve heat. In case the mixingtank is operated at superatmospheric pressure a suitable valve 16 may beprovided beneath hopper 1 and the tank is preferably provided with avent 11 controlled by valve 18 through which any incidental vaporsevolved from the hot materials in the mixing tank may pass to thefractionator or elsewhere, as desired.

As amodificatlon .of the .operation above described, intermediatecondensates from fractionator 29,- may comprise the only oil supplied toheating coil` I4,'in which case the chargingrstock mixture, includingwhendesired, high boiling oils removed from the lower portion offractionator 29, as already described, may be diverted from heating coilI4 and passed .from line I2 through line 14, valve T5 and line I8 to thecoking oven,

comminglingv in linev `I8 with the heated vinteri mediate condensatesfrom heating coil I4, which are, also discharged into the coking oven.It will be understood that, if desired, the heated oil from heating coilI4 and the charging stock mixture may be separately introduced into thecoking oven by well known means not shown in the drawing instead ofcommingling in linel I8 as illustrated.

When the charging stock mixture is supplied to the heating lcoil aconversion temperature measured at the outlet from this zone within therange of 850 to 900 F., is preferably ernployed, and preferably asubstantial superatmospheric pressure is employed in the heating coil,ranging for example from 100 to 500 pounds, or thereabouts, per squareinch measured at the outletY therefrom. A substantially reduced pressureis preferably employed in the cokng chambers, sub-atmospheric pressurebeing preferred in the coking Zone, although when desired substantiallyatmospheric or superatmcspheric pressure may be employed in this zone.The pressure employed in the coking zone may. be substantially equalizedin the succeeding fractionating, condensing and collecting portions ofthe system. When only intermediate condensates from the fractionator aresupplied to the heating coil more severe conversion conditions arepreferred in this zone, the temperatureat the outlet therefrom rangingfor example, from 925 to 1050" F., or thereabouts, preferably with asubstantial superatmospheric pressure at the outlet from the heatingcoil of from 200 to 800 pounds or more per square inch. The temperatureat which the materials. to be coked are heated in the coking ovens mayrange, for example, from 900 to 1200c F., or more, and when desired thecoke accumulated therein may be further devolatilized by employingtemperatures as high as 1600 F., or more in the coking oven after themixture of materials to be coked has been diverted therefrom, the cokingoven being isolated when desired from the rest of the system during thedevolatilizing operation.

As a specific example of the operation of the invention, the chargingstock is a mixture of about equal parts by weight of pulverized highvolatile bituminous coal and coal tar. The total combined feed suppliedto the heating coil comprises the charging stock mixture, the heavy highcoke-forming oils and the intermediate condensate removed from thefractionator and tar separator. The combined feed is subjected in theheating coil to an outlet temperature of approximately 900 F., at asuperatmospheric pressure of about 200 pounds per square inch and isintroduced into the coking ovens, which are operated at a substantialsub-atmospheric pressure and wherein the non-vaporous conversionproducts are reduced to coke at a temperature of approximately 1150" F.The accumulated coke may be further devolatilized at a temperature ofapproximately 1500D F.

An overhead product comprising motor fuel of about 400 F., end boilingpoint is recovered from the fractionator. This operation will produce,per ton of raw charging stock, about 1200 pounds of low volatile coke,approximately 55 gallons of motor fuel of good anti-knock value, andabout 5 20% by weight of gas suitable for use as fuel. The use of a fueloil from petroleum as a carrier for the coal will increase the yield ofmotor fuel and decrease the yield of coke and gas.

The conditions of operation and results shown are illustrative only andare not to be considered as limitations, as these may be varied widelywithout departing from the broad spirit and scope of the invention. p

I claim as my invention:

1. A process for the pyrolytic conversion and coking of finely dividedsolid bituminous material and hydrocarbon oil which comprises adding thesolid material to the oil, subjecting the mixture to conversiontemperature under substantially nonucts into a coking zone wherein theresidue is coked in a relatively thin layer upon a highly heatedsurface, subjecting the vaporous products from the coking zone tofractionation, whereby their components boiling above the range of thedesired final light distillate product of the process are condensed andseparated into selected low-boiling and higher boiling fractions,subjecting fractionated vapors of the desired endboiling point tocondensation, collecting and separating the resulting distillate and gasand returning the selected low-boiling fractions of the condensateresulting from said fractionation of the vaporous products to furtherconversion with the charging stock mixture and returning said higherboiling fractions for further treatment direct to the coking zone.

2. A process for the pyrolytic conversion and coking of nely dividedsolid bituminous material and hydrocarbon oil which comprises adding thesolid material to the oil, introducing the mixture into a coking zonewherein the volatiles of the coking conditions, introducing the heatedprod` mixture are substantially vaporized and the residue is reduced tocoke in a relatively thin layer upon a highly heated surface, subjectingthe vaporous products from the coking Zone to fractionation wherebytheir components boiling above the range of the desired final lightdistillate product of the process are condensed and separated intolow-boiling and higher boiling fractions, subjecting fractionated vaporsof the desired endboiling point to condensation, collecting andseparating the resulting'distillate and gas, returning said higherboiling fractions for further treatment direct to the coking zone,subjecting said low-boiling fractions of the condensate recovered byfractionation of the vapors to pyrolytic conversion under independentlycontrolled conditions o'f elevated temperature and superatmospherepressure and introducing the resulting products into the coking zone.

3. A process for the pyrolytic conversion and coking of finely dividedsolid bituminous material and hydrocarbon oil which comprises adding thesolid material to the hydrocarbon oil, subjecting the mixture toconversion temperature under substantially non-coking conditions,introducing the heated products into a coking zone wherein the residueis coked, subjecting the vaporous products from the coking zone tofractionation,

whereby their components boiling above the range of the desired finallight distillate product of the process are condensed and separated intoselected low-boiling and higher boiling fractions, subjectingfractionated vapors of the desired endboiling pointto condensation,collecting and separating the resulting distillate and gas and returningthe selected low-boiling fractions of the condensate resulting from saidfractionation of the vaporous products to further conversion with thecharging stock mixture and returning said higher boiling fractions forfurther treatment direct to the coking zone.

ALFRED FISHER.

